Device and process for producing undecylenic acid methyl ester using methyl ricinoleate as raw material

ABSTRACT

A device and a process for producing undecylenic acid methyl ester using methyl ricinoleate as raw material are provided. The device comprises a feed pump, a raw material pre-heater, a microwave catalytic reactor, a microwave generator, a temperature controller and an infrared sensor, a condenser, a product tank and a discharge pump. The feed pump is connected with the raw material pre-heater, which is connected with the inlet of the microwave catalytic reactor. The outlet of the microwave catalytic reactor is connected with the condenser, which is connected to the product tank and the discharge pump. The microwave catalytic reactor is located in the microwave generator, which is connected with the temperature controller and the infrared sensor. The process is as follows: high-purity methyl ricinoleate, used as the raw material, is converted to methyl undecene and heptaldehyde by microwave-assisted pyrolysis process, followed by isolation and purification to produce methyl undecene.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Chinese Patent ApplicationCN201410585158.X filed on Oct. 27, 2014.

TECHNICAL FIELD

The present invention relates to the field of lipid chemical productiontechnology, and particularly, to a device and a process for producingundecylenic acid methyl ester using methyl ricinoleate as raw material.

BACKGROUND

By means of saponification and acidification, undecylenic acid methylester can be obtained from undecylenic acid. Undecylenic acid hasextensive applications. Particularly, after bromide and ammonolysisundecylenic acid can become aminoundecanoic acid, which can bepolymerized to form tonylon-11 (PA11). PA11 has several advantages: ithas a low water absorption rate, is good in oil resistance, can wellwithstand low temperature, and is easy processing, etc. PA11 has beenwidely used in automotive industry, military industry, electrical andelectronic devices, sports equipment, food industry, medical devices,and so on. Undecylenic acid is used in large quantities in manufacturingflavors and fragrances. Musk T, which is made of undecylenic acid andhas strong musk fragrance, is the raw material for the remixing of thethree main synthetic flavors including the daily-use flavor. Inaddition, undecylenic acid also has a wide range of applications inmedicine and surfactant.

Currently, the production methods of undecylenic acid mainly includedirect pyrolysis of castor oil and pyrolysis of methyl ricinoleate. Themethod of direct pyrolysis of castor oil has some shortcomings such ashigh boiling point, high viscosity of castor oil and high pyrolysistemperature. The direct pyrolysis of castor oil in lead bath was onceused in China to produce undecylenic acid, with the reaction temperatureof higher than 600 degrees centigrade. Further issues with this processinclude serious coking and pollution, as well as low product yield.Since the 1980s, the direct catalytic cracking method has been studied;however, it still requires a temperature higher than 550 degreescentigrade and also has the issues of high cost of catalyst and lowreusing rate. The method for producing undecylenic acid used by theFrench company ATO is to crack methyl esterified castor oil under hightemperature, and method has already been industrialized. The technologyof producing nylon-11 from undecylenic acid is monopolized by ATO.However, it also has the issues of high cracking temperature and easycoking, and the yield is only about 30%. In Chinese Patent CN101289383A,an electric heater tower's cracking furnace was provided to directlycrack castor oil at the cracking temperature of 500˜600 degreescentigrade. It needs superheated steam of 500˜600 degrees centigrade,and the method has issues of high energy consumption, low productivity,low yield, and high equipment requirement.

Microwave heating is widely used in drying because of its uniqueadvantages: the process of microwave heating does not need directcontact to heat supply, or other intermediate conversion processes. Amicrowave absorbing material can be directly and quickly heated throughabsorption of microwave. Microwave heating can save electricity by up to30˜50% compared to conventional heating methods. The process ofproducing undecylenic acid methyl ester by pyrolysis of methylricinoleate under microwave heating has not been reported before.

SUMMARY

This invention intends to overcome the deficiencies of the knowntechniques and provides a device and a process for producing undecylenicacid methyl ester using methyl ricinoleate as raw material. The deviceand the process have advantages of low energy consumption, high productyield, and less coking. After transesterification and vacuumdistillation, castor oil can be converted into methyl ricinoleate ofgood fluidity and high purity. Using a microwave pyrolysis system,methyl ricinoleate can be quickly cracked to undecylenic acid methylester; then, isolation and purification processes are used to obtainhigh-purity undecylenic acid methyl ester.

The objective of the present invention is achieved by the followingtechnical scheme. The device for producing undecylenic acid methyl esterusing methyl ricinoleate as raw material comprises: a feed pump, a rawmaterial pre-heater, a microwave catalytic reactor, a microwavegenerator, a temperature controller and an infrared sensor, a condenser,a product tank and a discharge pump. The feed pump is connected with theraw material pre-heater, which is connected with the inlet of themicrowave catalytic reactor. The outlet of the microwave catalyticreactor is connected with the condenser, which is connected with theproduct tank and the discharge pump. The microwave catalytic reactormentioned above is located in the microwave generator, which isconnected with the temperature controller and the infrared sensor.

Preferably, the microwave catalytic reactor is designed with an inletand an outlet. The inlet and the outlet are arranged in the upper orside portion of the reactor. In addition, the microwave catalyticreactor can be made of glass, ceramics or any other wave-transparentmaterial that can stand high temperature.

Preferably, inside the microwave catalytic reactor is arranged a layerof microwave absorbing material. The microwave absorbing material may besilicon carbide, activated carbon, Fe/Co/Ni loaded alumina or zeolites,etc.

Preferably, the microwave catalytic reactor is arranged inside themicrowave generator, and the microwave generator is connected with afeed inlet, a product outlet and a temperature measurement port. Thefeed inlet, product outlet and temperature measurement port are arrangedon the top or the side of the microwave generator.

Preferably, the microwave generator is connected with the temperaturecontroller, the infrared sensor and a paperless recorder.

The present invention also provides a process for producing undecylenicacid methyl ester using methyl ricinoleate as raw material, withspecific steps as follows:

-   -   1. Set a cracking reaction temperature of the microwave        generator and turn on the microwave generator to start a heating        process;    -   2. Input into a device as mentioned above a methyl ricinoleate        of high purity using the feed pump of the device, regulating a        flow rate of the methyl ricinoleate using a flow meter and        heating the methylricinoleate using the raw material pre-heater;        the methyl ricinoleate of high purity may be obtained by        subjecting raw methyl ricinoleate to transesterification and        distillation;    -   3. At the set temperature and in the microwave catalytic reactor        of the device, methyl ricinoleate is quickly cracked into methyl        undecene and heptaldehyde gases; the methyl undecene and        heptaldehyde gases are conveyed into the condenser via the        outlet pipe; and    -    forming a liquid product by condensing the methyl undecene and        heptaldehyde gases using the condenser, conveying the liquid        product into the product tank and pumping the liquid product        into a distillation unit using the feed pump, and purifying the        liquid product to obtain the undecylenic acid methyl ester.

Preferably, the temperature of the cracking reaction is between 400 and600 degrees centigrade.

Preferably, the pyrolysis system is under atmospheric pressure ornegative pressure. This may be achieved by venting the product tank orconnecting it to a vacuum.

The beneficial effects of the present invention are as follows: 1. Theprocess of microwave heating does not need direct contact to heat supplyand other intermediate conversion process; microwave absorbing materialcan be directly and quickly heated through absorption of microwave;microwave heating can save electricity by up to 30˜50% compared toconventional heating methods. The present invention uses microwavegenerating device and microwave absorbing catalytic material, leading toa uniform heating process which can reduce energy consumption and carbondeposition. 2. Compared to other high-temperature pyrolytic devices andprocesses, the present invention eliminates lead pollution, shortensreaction time, improves reaction efficiency, and increases productyield.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram showing a device and a process according to thepresent invention.

FIG. 2 presents a gas chromatography-mass spectrometer (GC-MS) total ionchromatogram of raw material and products in microwave-assisted crackingof methyl ricinoleate at high temperature.

EXPLANATION OF THE REFERENCE SIGNS

-   1-1: feed pump-   2: raw material pre-heater-   3: microwave catalysis reactor-   6-1: microwave generator-   6-2: temperature controller-   6-3: infrared sensor-   6-4: condenser-   5: product tank-   1—discharge pump

PREFERRED EMBODIMENTS

A detailed description of a preferred embodiment of this invention ispresented as follows.

As shown in FIG. 1, the device for producing undecylenic acid methylester using methyl ricinoleate as raw material comprises, among otherparts, a feed pump (1-1), a raw material pre-heater (2), a microwavecatalysis reactor (3), a microwave generator (6-1), a temperaturecontroller (6-2) and an infrared sensor (6-3), a condenser (4), aproduct tank (5) and a discharge pump (1-2). The feed pump (1-1) isconnected with the material pre-heater (2), which is connected to theinlet of the microwave catalytic reactor (3). The outlet of themicrowave catalytic reactor (3) is connected with the condenser (4),which is connected to the upper port of the product tank (5). The lowerport of the product tank (5) is then connected to the discharge pump(1-2). The microwave catalytic reactor (3) is placed in the microwavegenerator (6-1), which is connected with the temperature controller(6-2) and infrared sensor (6-3), and also a paperless recorder ifnecessary.

The microwave catalytic reactor (3) mentioned above has an inlet and anoutlet, which are located on the top or the side of the microwavecatalytic reactor (3). The microwave catalytic reactor (3) can be madeof glass, ceramics or other wave-transparent material that can withstandhigh temperature. Inside the microwave catalytic reactor (3) is a layerof microwave absorbing material, which can be silicon carbide, activatedcarbon, Fe/Co/Ni loaded alumina or zeolites. The microwave catalyticreactor (3) is arranged inside the microwave generator (6-1), and themicrowave generator (6-1) is connected with a feed inlet, a productoutlet and a temperature measurement port. The feed inlet, the productoutlet and the temperature measurement port are arranged on the top orthe side of the microwave generator (6-1).

A process for producing undecylenic acid methyl ester using methylricinoleate as raw material comprises the specific steps as follows:

-   -   1. Set a cracking reaction temperature of the microwave        generator (6-1) at 400˜600 degrees centigrade and turn on the        microwave generator (6-1) to start the heating process;    -   2. Input into a device as mentioned above a methyl ricinoleate        of high purity using the feed pump (1-1), regulating a flow rate        of the methyl ricinoleate using a flow meter and heating the        methyl ricinoleate using the raw material pre-heater (2); the        methyl ricinoleate of high purity may be obtained by subjecting        raw methyl ricinoleate to transesterification and distillation;    -   3. At the set temperature and in the microwave catalytic reactor        of the device, methyl ricinoleate is quickly cracked into methyl        undecene and heptaldehyde gases; the methyl undecene and        heptaldehyde gases are conveyed into the condenser (4) via the        outlet pipe; and    -    forming a liquid product by condensing the methyl undecene and        heptaldehyde gases using the condenser, conveying the liquid        product into the product tank (5) and pumping the liquid product        into a distillation unit using the feed pump (1-2), and        purifying the liquid product to obtain the undecylenic acid        methyl ester.

As an embodiment of the invention: at 60 degrees centigrade, castor oilis mixed with an alkali solution of methanol to start thetransesterification reaction. After 1 hour, the oil phase obtained fromlayering is washed with water until its pH=7. Then, rotary evaporationis performed to remove the methanol and the trace water, to obtain crudemethyl ester containing 87% (by weight) of methylricinoleate. The crudemethyl ester is then distilled at the reduced pressure of 100 PaA andreflux ratio of 5, during which temperature at the bottom of thedistillation device is controlled at 190˜210 degrees centigrade and thetemperature at the top of the distillation device is controlled at about170 degrees centigrade. The purity of the methylricinoleate obtained ishigher than 99%, and the methylricinoleate obtained is used as thefeedstock, or the raw material, for the subsequent microwave pyrolysis.

Silicon carbide is input to the microwave catalytic reactor (3), and thetemperature of the microwave generator (6-1) is set at 500 degreescentigrade. The feed tube N is connected to the import port E of themicrowave catalytic reactor (3) and the outlet tube O is connected tothe export port F of the microwave catalytic reactor (3). The export Fis then connected with the condenser (4), on which the ports J and I arethe import and export of freezing water, respectively. The microwavegenerator (6-1) is turned on to make the microwave absorbing material inthe microwave catalytic reactor (3) reach the set temperature andstabilize for a period of time. The raw material (high-purity methylricinoleate) is pumped by the feed pump (1-1), the flow rate of the rawmaterial is measured or regulated by the flow meter, the raw material isheated by the raw material pre-heater (2), and then enters the microwavecatalytic reactor via the inlet 3E thereof, and is cracked in themicrowave catalytic reactor. On the raw material pre-heater, port 2A, B,C, and D are the feed port, discharge port, outlet of heat transfer oil,inlet of heat transfer oil, respectively. At the set temperature, theraw material is quickly cracked into methyl undecene and heptaldehydegases, which flow through the outlet F into port 4G of the condenser.The methyl undecene and heptaldehyde gases are condensed in the condenseto form a liquid, which flows out of the condenser through port H andenters the product tank through port K. Port L of the product tank canbe vented or vacuumed or connected to a vacuum to provide a negativepressure for the pyrolysis system. The pyrolysis system may be underatmospheric pressure or negative pressure. This may be achieved byventing the product tank or connecting it to a vacuum. The liquid ispumped into a downstream distillation unit by the feed pump (1-2), andisolation and purification processes can be carried out on the liquid toobtain high-purity methyl undecene, and saponification and acidificationprocesses may follow to finally obtain the undecylenic acid. Results ofthe embodiment are as follows: the liquid yield is 90.5%; the yield ofthe undecylenic acid is 70.2%; and selectivity of the undecylenic acidis 80.5%. By comparison, the yield is only 34˜38% in the electricalheating process as reported by Chinese patent CN101289383A, and theyield in the melting lead process is only 30˜32%. Compared with theseprocesses, the yield of undecylenic acid in the present invention can beat least doubled.

It can be understood that as for technical staff in the present field,equivalent replacements or changes to the technical scheme or inventiveconcept in the present invention should be protected according to theclaims in the present invention.

What is claimed is:
 1. Device for producing undecylenic acid methylester using methyl ricinoleate as raw material, comprising: a feed pump,a raw material pre-heater, a microwave catalysis reactor, a microwavegenerator, a temperature controller and an infrared sensor, a condenser,a product tank and a discharge pump; wherein the feed pump is connectedwith the material pre-heater, which is connected to an inlet of themicrowave catalytic reactor; wherein an outlet of the microwavecatalytic reactor is connected with the condenser, which is connected toan upper port of the product tank; wherein a lower port of the producttank is connected to the discharge pump; wherein the microwave catalyticreactor is arranged in the microwave generator, which is connected withthe temperature controller and the infrared sensor.
 2. The deviceaccording to claim 1, wherein the inlet and the outlet of the microwavecatalytic reactor are arranged in the upper or side portion of themicrowave catalytic reactor.
 3. The device according to claim 1, whereinthe microwave catalytic reactor is made of glass, ceramics or otherwave-transparent material that can withstand high temperature.
 4. Thedevice according to claim 1, wherein a layer of microwave absorbingmaterial is arranged inside the microwave catalytic reactor.
 5. Thedevice according to claim 4, and the microwave absorbing materialcomprises any one of silicon carbide, activated carbon, Fe/Co/Ni loadedalumina and zeolites.
 6. The device according to claim 1, wherein themicrowave catalytic reactor is arranged inside the microwave generator.7. The device according to claim 6, wherein the microwave generator isconnected with a feed inlet, a product outlet and a temperaturemeasurement port arranged on the top or the side of the microwavegenerator.
 8. The device according to claim 1, wherein the microwavegenerator is connected with the temperature controller, the infraredsensor, and a paperless recorder.
 9. A process for producing undecylenicacid methyl ester using methyl ricinoleate as raw material and employingthe device of claim 1, the processing comprising the steps asfollows: 1) setting a cracking reaction temperature of the microwavegenerator, and turning on the microwave generator to start a heatingprocess; 2) inputting into the device a methyl ricinoleate of highpurity using the feed pump, regulating a flow rate of the methylricinoleate using a flow meter and heating the methyl ricinoleate usingthe raw material pre-heater; 3) at the set temperature and in themicrowave catalytic reactor, cracking the methyl ricinoleate of highquality into methyl undecene and heptaldehyde gases, and conveying themethyl undecene and heptaldehyde gases into the condenser via the outletpipe; and 4) forming a liquid product by condensing the methyl undeceneand heptaldehyde gases using the condenser, conveying the liquid productinto the product tank and pumping the liquid product into a distillationunit using the feed pump, and purifying the liquid product to obtain theundecylenic acid methyl ester.
 10. The process of claim 9, furthercomprising the step of subjecting raw methyl ricinoleate totransesterification and distillation to provide the methyl ricinoleateof high purity.
 11. The process according to claim 9, wherein thetemperature of the cracking reaction is between 400 and 600 degreecentigrade.
 12. The process according to claim 9, wherein the pyrolysissystem is under atmospheric pressure or negative pressure.
 13. Theprocess according to claim 12, further comprising a step of venting theproduct tank or connecting it to a vacuum so as to provide theatmospheric pressure or negative pressure for the pyrolysis system.